Measles

Test code(s) 689, 964, 34166, 34256

Question 1. When should I evaluate a patient for measles (rubeola)?

Any patient who presents with a clinical syndrome consistent with measles, irrespective of potential exposure or travel history, should be evaluated for measles. While most cases in an outbreak situation have occurred in nonimmunized people, there have been documented cases in previously vaccinated people.

Signs and symptoms include fever with runny nose or congestion, cough, conjunctivitis, malaise, and a rash that typically emerges a few days after onset of illness. The incubation period is 7-21 days and, on average, the rash appears about 14 days after exposure to the virus. Affected patients are contagious 4 days before to 4 days after the rash appears.

Question 2. What should healthcare providers do when they have a patient with suspected measles infection?

Public health authorities are asking healthcare providers to notify them directly if they have a patient with suspected measles. This allows them to track highly suspect cases and provide appropriate public health follow up. For highly suspect cases, local public health departments will recommend appropriate testing procedures.

Question 3. Which laboratory tests are used for measles diagnosis?

The most common tests used for diagnosing measles are the measles antibody (IgM) test and the measles RNA real-time polymerase chain reaction (RT-PCR) test. Viral culture is an alternative method if PCR is not available.

A positive RT-PCR test or a positive culture confirms the diagnosis. While detection of IgM antibody can be diagnostic, false-positives may occur, especially in low prevalence populations. Conversion of a negative to a positive antibody result or a four-fold or greater increase in measles antibody titer in acute and convalescent serum specimens are diagnostic.

Question 4. Which tests does Quest Diagnostics offer?

Quest Diagnostics offers the following options:

Measles Antibody (IgM), test code 34256

Measles Antibody (IgG), test code 964

Measles Antibodies (IgG, IgM), test code 34166

Culture, Viral, Body Fluids, Tissues, test code 689

The measles IgM test is suitable for diagnosing acute infection, while the IgG test is used to diagnose immunity following infection or vaccination. Culture can be performed using nasopharyngeal (NP), throat, and urine specimens. Detailed specimen collection instructions for culture can be found at QuestDiagnostics.com. When ordering culture, please note “rule out measles” on the requisition.

Question 5. Does Quest Diagnostics offer a measles RNA RT-PCR test?

Quest Diagnostics does not currently offer PCR testing for measles diagnosis. PCR testing is available at the CDC and at some public health laboratories. Clients can contact their local or state health departments to find out about molecular testing options and specimen collection requirements. Specimen collection information for RT-PCR testing can also be found at the CDC website.

This FAQ is provided for informational purposes only and is not intended as medical advice. A clinician’s test selection and interpretation, diagnosis, and patient management decisions should be based on his/her education, clinical expertise, and assessment of the patient.